1. Field of the Invention
The present invention relates to the delivery of ophthalmic lenses.
2. Description of the Prior Art
Intraocular lenses are implanted into the eye through very small incisions in the eye, usually in the cornea, the lenses being rolled into a spiral or cylindrical shape prior to delivery.
Delivery can be carried out using a delivery device which is controlled manually by a surgeon, employing either a one-handed or a two-handed technique.
In many delivery devices substantial manual force can be required to progress the lens through the device. This can lead to difficulties for the surgeon as the procedure requires a great deal of control at the final stage of lens delivery, this often being as a result of the lens delivery device having a tapered cavity through which a rolled lens is progressed linearly prior to delivery into the eye, the degree of rolling of the lens being increased by the tapering of the cavity.
The lack of control at the final stage of delivery is an issue particularly associated with one-handed delivery techniques. These techniques usually involve delivery of a lens by depression of a plunger by the surgeon to progress the lens through the device and into the eye. This offers the advantage of freeing the surgeon's other hand for other actions.
An alternative is the two-handed technique of lens delivery. This usually involves delivery of a lens by rotation of a threaded plunger by the surgeon to produce linear motion in order to progress the lens through the device and into the eye. This technique offers the advantage of greater control of the delivery but with the disadvantage restricting the surgeon's freedom to perform other tasks using his other hand.
WO 2011/126144 A1 (Hoya Corporation) discloses an ocular implant insertion apparatus configured for screw-type and push-type operation. The apparatus has a body and a plunger, one of which has a helical slot and a longitudinal groove which intersects the slot. The other of the body and plunger has a protrusion which fits within the groove or the slot. The apparatus is switched between the two types of operation by visual alignment by the user of appropriate parts of the apparatus.
US 2009/0112223 A1 (Downer et al) discloses a lens delivery system handpiece having a threaded plunger rod with a ball lock ring. Locking the ring causes the plunger to be advanced by turning a thumbscrew or knob. Unlocking the ring allows the plunger to be advanced by pushing on the thumbscrew or knob in a manner similar to a syringe.